Sewing machine



W. A. AYRES SEWING MACHINE Aug. 26, 1958 Filed Jan. 25. 1954 INVENTOR. Mme-M42 ,4 flyees 1 I 4rroe-sy5 United States Patent SEWING MACHINE Waldemar A. Ayres, Lakewood, Ohio, assignor to White Sewing Machine Corporation, Lakewood, Ohio, a corporation of Delaware Application January 25, 1954, Serial No. 405,724

6 Claims. (Cl. 112-231) This invention relates to a sewing machine and more particularly to an improved bobbin case that is used in conjunction with the rotary hook or loop taker of the sewing machine and which mounts the bobbin for the lower thread.

As is well understood in the art sewing machines have a rotary hook or loop taker located beneath the bed plate of the machine and provided with a hook or beak that engages and manipulates the loop of the upper thread as the needle passes through the material being sewn and through the bed plate to the lower side thereof.

The rotary hook or loop taker mounts a bobbin case in which the bobbin for the lower thread is located. The bobbin case is held against rotation, wherefore the rotary hook or loop taker rotates relative to the bobbin case and bobbin as will be well understood.

it is customary to provide on the head of the sewing machine means for tensioning the upper thread and such means in some instances has been in the form of a pulley around which the upper thread is wrapped and which pulley can rotate but is retarded in its rotation by adjustable friction retarding means.

It has also been customary to provide atensioning means on the bobbin case for the lower thread and such tensioning means has usually been in the form of an arcuate spring plate or finger surrounding a portion of the circumference of the side wall of the bobbin case while the lower thread from the bobbin passes between the, side wall of the bobbin case and such tensioning means. However, the usual tensioning means employed on the bobbin case for the lower thread does not give the optimum result. Sewing threads frequently vary in diameterat diiferent longitudinal locations or have imperfections therein such as lumps or the like. Although the variations in diameter of the sewing thread and the lumps or other imperfections which might be therein are minute they do affect the properfunctioning of the usual thread tensioning means'for the lower thread since whenlargediameter portions of the thread or portions thereof which have imperfections pass between the thread tensioning means and theside wall of the bobbin case an undesired retarded action or increased tension is placed on the lower thread and this affects the sewing efficiency of the machine. The same objection or disadvantage is not present with respect to. the thread tensioning means for the upper thread which includes the pulley around which the thread extends and the rotation of which is frictionally resisted.

An object of the invention is to provide in a bobbin case an improved and novel tensioning means for the lower thread and which means is not affected by variations in thread thickness or by imperfections in the thread.

A further object is toiprovide in a bobbin case improved and novel tensioning means for the lower thread and which meansfunctions so as to produce a constant degree of tension on the thread throughout'the sewing operation.

Another object of the invention is to provide in a i its:

bobbin case thread tensioning means for the lower thread which can be readily adjusted to give ditferent desired and correct degrees of thread tension for different types of sewing operations and which thread tensioning means after each adjustment will cause the tension on the lower thread to be uniform throughout the sewing operation for the selected or adjusted thread tension suitable for that operation.

A further object of the invention is to provide an improved and novel bobbin case and thread tensioning means therein for a sewing machine and which thread tensioning means includes a rotatable pulley around which the lower thread extends and adjustable means for frictionally resisting the rotation of the pulley and so constructed as to be accommodated within the bobbin case, notwithstanding the limited space available for such purpose.

A still further object of the invention is toprovide a bobbin case such as hereinbefore referred to and a rotary hook or loop taker for assembly with the bobbin case and wherein the bobbin case and rotary hook or loop taker are so formed as to cause the lower thread from the bobbin to ride over the rotary hook or loop taker and the bobbin case freely and correctly and to prevent such thread from undesirably'passing through openings or slots in the bobbin case andbecome entwined or interlocked with the parts thereof that would affect the efiiciency of the bobbin case and.the rotary hook or loop taker.

A still further object of the invention is to'provide an improved and novel bobbin case which has incorporated in it a single means for releasably maintaining the bobbin case in operative position within the rotary hook or loop taker and for releasably maintaining the bobbin in the bobbin case when the bobbin case is being removed from or positioned in the rotary hook' or loop taker.

A still further object is to provide an improved and novel bobbin case as specified in the hereinbefore mentioned objects and which is of simple construction, is easily assembled or disassembled, is efiicient in operation and can be readily positioned in or removed from the rotary hook or loop taker.

Further and additional objects and advantages not hereinbefore referred to will become apparent hereinafter during the detailed description of an embodiment of the invention that is illustrated in the accompanying drawings forming part of this specification and wherein:

Fig. 1 is a side elevational view of the rotary hook or loop taker for a sewing machine with the bobbin case embodying the invention mounted therein, it being understood that the rotary hook and the bobbin case are illustrated as enlarged over actual size.

Fig. 2 is a plan view of the rotary hook and bobbin case shown in Fig. 1 and is taken looking from the right hand side of Fig. 1.

Fig. 3 is a sectional view taken on irregular line 3-3 of Fig. 2 looking in the direction of the arrows.

Fig. 4 is a view on an enlarged scale partly in section and partly in plan taken approximately on line 4-4 of Fig. 3 looking in the direction of the arrows, with certain of the parts broken away at different levels to clearly illustrate the construction thereof.

Fig. 5 is a fragmentary sectional view of a portion of Fig. 3 but on an enlarged scale to. clearly illustrate the details of the construction, and

Fig. 6 is a detached perspective view of one of the friction rings with a portion of the friction coating on said ring broken away.

The rotary hook or loop taker for the most part is of substantially conventional construction except as to several features which will be hereinafter specifically referred to. The rotary hook or loop taker is'indicated generally at and includes the usual hook or beak 11. As will be well understood in the art, the rotary hook or loop taker 10 is located for rotation beneath the bed plate of the sewing machine and in a position with respect to the path of movement of the reciprocating needle such that the hook or beak 11 will engagcthe loop in the upper threadwhen the needle is below'the bed plate in its reciprocation and will manipulate such loop so as to interlock it with the lower thread. Also, as is well known, the rotary hook or loop taker will be driven by the: sewing machine drive mechanism at the correct rate of rotation correlated to the other moving parts of the machine.

The side wall 12 of the rotary loop taker or hook 1!) curves inwardly toward its upper end so as to be of approximately conical configuration. The side wall 12 adjacent to the beak or hook 11 is provided in its upper edge with a round or curved portion 13 which facilitates the passage of the thread upwardly over and across the bobbin casewhich is mounted in the rotaryhook.

The rotary hook or loop taker 10 is provided interiorly with a central post 14 which adjacent its base has a reduced diameter portion 14a which merges into the normal diameter of the post with an outwardly extending curve 1412, the purpose of which will later become apparent. The rotaryhook 10 except as above specified is of conventional construction.

The bobbin case is of generally cylindrical cup-shaped configuration and includes an end or bottom wall 15 and a cylindrical side wall 16 which extends a short distance beyond the end wall 15 to provide an annular rim 17, the outer. circumference of which rim being curved as indicated at 17a and which will be referred to hereinafter.

The rim 17 is provided with circularly spaced notches or grooves 18 through which the thread from the bobbin passes, as will later be. explained, and intermediate said notches or grooves 18 it has a wide notch or slot 19, see Figs. 2 and 4, the purpose of which will later be explained.

The end or bottom wall 15 of the bobbin case is provided with "a central opening through which passes a sleeve 20 that is open at one end and closed at its opposite end, said closed end being indicated at 20a. The sleeve 20 inwardly of but adjacent to its closed end 20a is provided with an external annular flange 21 which when the sleeve is mounted in the end wall 15 engages said end wall'within the cup-shaped bobbin case. The flange 21 may be integral with the sleeve 20 or it may be a separate element fixedly secured to the sleeve.

The closed end 20a of the sleeve 20 is threaded so that an internally and externally threaded clamping nut 22 can be screwed thereon to clamp the sleeve in position and secured to the end wall 15 with the flange 21 engaging one side of the end wall and the end of the internally, externally threaded nut 22 engaging the opposite side of the end wall. a

The sleeve 20 is provided with a longitudinally extending slot in which a spring finger 23 is located, with one end of said spring finger rigidly secured to the sleeve 20 and with the other end thereof having a detent head 24 provided with a detentportion 24a extending into the interior of the sleeveand a detent portion 24b which extends to the exterior of the sleeve.

When the bobbin case is mounted in the rotary hook or loop taker the sleeve 20 telescoped upon the post 14 during which action the detent. portion 24a of the detent head 24 will snap'into engagement with the curved portion 14b. of .the post 14 and frictionally hold the bobbin case in the rotary hook. However, when it is desired to remove the bobbin case from the rotary hook an outward pull on the bobbin case will overcome the holding friction of the detent head 24 and cause the spring finger 23 to be flexed outwardly by the post 14. 'Thedetent head 24 in addition to serving as the retaining elementfor the bobbin case in the rotary book also functions to retain' the bobbin in the bobbin case when thebobbin case is being applied to or removed from the rotary hook and alsowhen the bobbin case is assembled in the rotary hook.

Reference to Fig. 5 will show that the detent portion 24b of the detent head 24 of the spring finger 23 engages the end of the hub of the bobbin 25 while the other end of the hub of the bobbin engages the flange 21 of the sleeve. The detent head 24 of the spring finger 23, and particularly the detent portion 24b thereof, functions at all-times to hold the bobbin in position in the bobbin case. When the bobbin case is being removed from or is being positioned in the rotary hook and the detent portion 24a is in contact with the larger diameter portion of the post 14 of the rotary hook the spring finger 23 will be flexed so that the detent portion 24b will extend further across the end of the hub of the bobbin 25. Even when the detent head 24 is free to move inwardly when the detent portion 24a engages the curved portion 14b of the post 14, the detent portion 24b of the spring finger will still be in engagement with the end of the hub of the bobbin. Hence the bobbin is retained in the bobbin case at all times until it is 'desired to remove the same from the bobbin case. The removal of the bobbin from the bobbin case occurs, of course, when the bobbin case has been removedfrom the rotary hook and the spring finger 23 is at its inner limit of flexing movement, at which time the detent portion 24b thereof is still in engagement with the end of the hub of the bobbin. However, the bobbin can be readily removed bygrasping the same and withdrawing it from off of the sleeve 20, it requiring only a slight pull to cause the end of the bobbin hub to cam the *dctent'head 24 inwardly of the sleeve and free the bobbin for removal.

The present invention contemplates including in the bobbin case a thread tensioning means for the lower thread and which means includes a rotatable pulley around which the lower thread extends and adjustable friction means resisting the rotation of the pulley and acting to place a predetermined tension on the thread.

A friction ring 26 is mounted over the clamping nut 22 and bears against the end wall 15 of the bobbin case. Thisfriction ring may take various forms but for illustrative purposes a form which is now considered the preferred one. will be explained. The presently preferred form of friction'ring comprises a thin metal ring26a whichmay be formed of various suitable materials and in different sizes but which preferably will be a ring stamped from a sheet ofv metal foil such as extremely thin brass foil. The metal ring 2611 also includes, at least on one side although it may be coated on both sides, aeoating 26b of suitable friction material. In forming the friction ring 26 preferably a sheet of the metal foil is coated with the friction material and thereafter the friction ring 26 is stamped from the coated sheet of foil. The coating of friction material may be applied to the foil in any suitable way as, for instance, it may be secured thereto by an adhesive and the coating may be formed of any suitable material. However, it is contemplated as a preferred practice to electrostatically deposit the coating on the sheet of metal foil as thishas been found to effect the properdeposition of the coating and the necessary adhesion of the coating to the metal foil. In fact, the electrostatic deposition of the coating on the foil appears to integrate the coating with thefoil.

As a preferred material for the coating it is contemplated using nylon lint or dust, and it has been found that the fibers of the nylon lint or dust readily respond to the clectrostaticaction and form a suitablefcoating thathas the required friction characteristics.

As shown in Figs. 3 and 5, the friction disk 26 is mounted with the metal foil 26a adjacent to the end wall 15 of the bobbin case and with the friction material coating ;-26b remote thereto; A bearing sleeve 27 prois nonrotatably mounted on the nut 22, said sleeve27 being provided with diametral opposite interior flats which cooperate with the diametrically opposite wrench flats 2211 on the nut 22 to maintain the sleeve 27 against rotation. The sleeve 27 has slight limited movement axially of the nut.

A pulley is rotatably mounted on the sleeve 27 and comprises a hub 28 that is provided at one end with a flange 28a and which flange when the parts are assembled contacts the friction material 26b of the friction ring 26, see Fig. 5. The pulley also includes a ring disk 29 that is mounted on the hub 28 and is held tightly against the flange 28a of the hub by a retaining ring 30 that has a pressed fit on the hub. The disk ring 29 outwardly of the circumference of the flange 28a of the hub and of the retaining ring 30 is radially slotted as indicated at 31 in Fig. 4 with a series of circularly spaced slots. The slots 31 provide a multiplicity of circularly spaced fingers 32 and these fingers are alternately bent out of the plane of the ring disk 29 first in one direction and then in the opposite direction and provide a circular V-shaped pulley groove around which and in which may extend the thread from the bobbin.

A second friction disk 26 is mounted on the sleeve 27 intermediate the end of the hub 28 and retaining ring 30 and the sleeve flange 27a, see Fig. 5. This second friction ring has its friction material coated side 26b arranged in contact with the end of the hub 28 and with the retaining ring 30 while the metal foil side 26a of the friction retaining ring engages the flange 27a of the sleeve 27. A means for adjusting the frictional contact between the frictional surfaces 26b of the two friction rings 26 and the hub 28 and retaining ring 30 of the pulley will now be described.

This friction adjusting means is shown as in the form of a ring 33 that is provided in its central opening with a partial thread, wherefore the ring can be screwed onto the exterior of the nut 22 and turning on the ring thereon will cause it to be moved inwardly or outwardly of the nut. The ring 33 engages the flange 27a of the sleeve 27 and hence its movement inwardly and outwardly of the nut will move the sleeve axially and vary the degree of frictional contact between the friction coatings of the two friction rings 26 and the hub 28 and retaining ring 30 of the pulley to thus vary the resistance to rotation of the pulley and the degree of tension on the lower thread from the bobbin.

The tension adjusting ring 33 is provided on its circumference with a radialy outwardly extending pointed finger 34 which, as will later be explained, is accessible to the user of the machine so that he can grasp said finger and rotate the ring 33 in the required direction to vary the degree of friction to the rotation of the pulley to that which is desired for a particular sewing operation.

The ring 33 is split as indicated at 35 and the ring is tensioned so as to frictionally grip the exterior threads of the nut 22, wherefore the ring will remain in any position of adjustment to which the operator moves it.

A dish-shaped cap 36 is secured to the bobbin case and overlies the tension adjusting ring 33. The cap 36 is provided centrally thereof with a threaded opening into which can be screwed a screw 37 that passes through a central opening in the closed end a of the sleeve 20 and has its slotted head located within the sleeve 20. It will be noted that a suitable screwdriver can be inserted into the sleeve 20 and engaged in the slotted head of the screw 37 and the latter turned to secure the cap to the assembly or to allow the cap to be removed therefrom.

The cap 36 is provided on its crown and cefitrally thereof with finger grip recesses 38 whereby the operator can hold the bobbin case with the bobbin retained therein in applying the bobbin case to the rotary hook or in removing the same therefrom, it being recalled that the snap action of the detent head 24 of the spring finger 23 permits of such application to or removal from the rotary hook..

The cap 36 is provided with an outwardly and radially extending finger 39 that interfits the slot.19 in the rim 17 of the bobbin case and which extends beyond the bobbin case and is adapted to be engaged by a fixed portion of the sewing machine beneath the bed plate to hold the bobbin case against rotation while the rotary hook rotates relative thereto as will be well understood in the art.

The cap 36 is also provided adjacent to the finger 39 with an arcuate slot 40 through which the pointed finger 34 of the tension adjusting ring 33 extends, wherefore the finger is accessible to the operator and the latter can turn the ring 33 to adjust the frictional resistance to the pulley rotation and the tension on the lower thread.

If desired, the cap 36 may be provided with graduation marks and indicia characters representing different degrees of tension adjustment so as to guide and help the operator in adjusting the ring 33 to the proper positions for the different degrees of thread tension required for particular types of sewing operations. It will be noted that the curved wall of the cap 36 extends into the exterior of the rim 17 of the bobbin case and is overlapped thereby wherefore the thread passing over the bobbin case will be guided across the top of the cap and will not get in between the cap and the remainder of the bobbin case.

The thread from the bobbin 25 passes outwardly of the bobbin case through an opening 41 in the wall 16 and then it passes through one of the grooves 18 in the rim 17 and can be passed around the pulley in the V-shaped groove between the fingers 32 thereof readily and easily and thence oif of the pulley and through the other groove 18 as indicated in Fig. 4.

The cap 36 is provided with a circumferentially located slightly cutaway portion 42 to facilitate the passage of the thread by the operator between the cap and the rim 17 in the operation of Wrapping the thread in the annular V-groove between the finger 32 of the pulley.

Although a preferred embodiment of the invention has been described it will be understood that the invention is susceptible of various modifications and adaptations within the scope of the appended claims.

Having thus described my invention, I claim:

l. A bobbin case for use with the rotary hook of a sewing machine comprising a substantially cup-shaped member within which the bobbin may be mounted and from the exterior of the bottom wall of which extends a centrally disposed externally threaded supporting portion, a friction ring mounted on said portion and engaging the exterior of the bottom Wall of said member, a sleeve nonrotatably mounted on said portion and having limited axial movement thereon, a pulley having a hub rotatably supported by said sleeve, said sleeve being provided at its outer end with a radially disposed flange, said friction ring contacting one side of said hub, a second friction ring located on said sleeve intermediate said hub and said flange and engaging said hub and flange, and means screwed on said exterior threads of said supporting portion outwardly of said sleeve and flange and engaging the latter whereby said means can be adjusted inwardly or outwardly of said portion to vary the pressure between said hub and said rings to vary the tension on the thread withdrawn from the bobbin and wrapped around said pulley.

2. A bobbin case as defined in claim 1 and wherein said pulley includes a hub rotatable on said sleeve and a disk fixed to said hub and provided with a series of circularly spaced radial slots extending inwardly from the circumference of said disk and forming a series of circularly spaced fingers, said fingers alternately being bent in opposite directions out of the plane of said disk to provide a substantially V-shaped pulley groove in which the thread from the bobbinmaybe wrapped.

3. A bobbin case as defined in claim 1 and wherein said :friction rings include a thin metal foil ring having a -friction coating thereon which is inengagement'with the hub of the pulley.

4. A bobbin casetas defined in claim 1 and wherein said pulley'includes'a hub formed of a cylindrical memberhavingat one end a radially extending flange, a clamping ring-secured on said'cylindrical member, and a disk clamped between the flange of said cylinclrimal member and said clamping ring.

5. A-bobbin case for use'with a rotary hook of a sewing machine comprising a substantially cup-shaped member having a centrally disposed sleeve secured to the bottom-wall of said member and provided with a portion located within thecup-shaped member and adapted to have the bobbin mounted thereon and a portion extendingbeyond the bottom wall of said member, an external- 1y threaded'supporting element mounted on said last named portion of said sleeve, a cylindrical bushing nourotatably mounted on said element but having limited axial movement relative thereto and provided at its outer endiwithia radial flange, a pulley rotatable on said bushing; a friction ring mounted on said bushing intermediate said pulley and said bushing flange and engaging the same, an adjustable ring provided with .a partial thread and screwed on said supporting element outwardly of said bushing andacting to vary the frictional contact between said friction ring and said'pulley, a cap secured to the last-mentioned portion of said sleeve and-overlying said adjustable ring and provided wit-h an 'arcuate slot, said adjustable ring being provided with a portion projecting from thecircumference-thereof and extending through said slot.

6. A bobbin case as defined in claim5 and wherein the bottom wall of thecup-shaped member exteriorly of said-memberis provided'with a circumferential bead or flange, While said capadjacent its circumference is curved toward said bottom wall of said cup-shaped member and extends within and'closelyadjacent said bead or flange, whereby threadfrom the bobbin will be guided by the header flange upwardly .of'said cap.

References Cited in the file of this patent UNITED STATESPATENTS 

